from PyQt5 import QtWidgets

from background_demo import Ui_Form
import img_rc

if __name__=="__main__":
    import sys
    app=QtWidgets.QApplication(sys.argv)
    widget=QtWidgets.QWidget()
    ui=Ui_Form() #假定该.py中的类名为Ui_Form
    ui.setupUi(widget)
    widget.show()
    sys.exit(app.exec_())